But the government citations don't conclude that the violations caused the blast.

Citations issued Thursday and released Friday say the company exposed workers to serious hazards that were likely to cause death or serious physical harm, The Dallas Morning News reported in Saturday editions.

Bellville-based Western International Gas & Cylinders was delivering acetylene, a gas used in welding, on July 25 when its tractor-trailer exploded, severely burning two workers, causing more than $2.3 million in damage and sending plumes of smoke higher than some skyscrapers.

OSHA said the Southwest Industrial Gases plant could have reduced the fire risk by putting in a sprinkler system in the loading dock. The plant wasn't required to have fire sprinklers because it was built before new fire codes took effect.

Southwest Industrial has said that a delivery company driver hooked up the supply system wrong and then ran from a hissing gas leak.

The agency cited the company for two other violations: failing to properly mark trucks that carried pallets of acetylene cylinders and having a hazard analysis that was conducted only by the general manager, instead of by a team of employees.

"None of those violations led to the accident," said Melvin Ruyle, the company's former president, told the newspaper. "We had over 30 years of successfully running the plant with no problems."

Ruyle said he stepped down last week, putting another official, Waco Mayor Virginia DuPuy, in charge.

Two workers at the Dallas explosion received second- and third-degree burns. One of the injured workers told investigators he thought the explosion started with a crack in a tank connection.

Dallas Fire-Rescue has said that either mechanical failure or human error caused the break in a cylinder and hookup connection that allowed the acetylene to "self-ignite."

Less than three weeks later, a Western International trailer full of canisters burst into flames during a delivery in The Woodlands near Houston.